Distributed vehicle lidar system

ABSTRACT

A distributed FM LiDAR system that provides a central unit that includes a frequency modulated optical signal source and a central receiver for reflected light, along with multiple optical heads that include only optical components is described. No optical delay lines or timing compensation photonic or electronic circuitry is necessary between the central unit and the optical heads. The relatively simple optical heads do not require extensive protection from shock or vibration, and can be distributed between a vehicle and a towed trailer or similar vehicle, with connections being provided by an optical coupling.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/236,572, filed Dec. 30, 2018, and entitled “DISTRIBUTED VEHICLE LIDARSYSTEM”, which is a continuation of U.S. patent application Ser. No.15/663,506, filed Jul. 28, 2017, and entitled “DISTRIBUTED VEHICLE LIDARSYSTEM”, which claims the benefit of U.S. Provisional Application No.62/367,815, filed on Jul. 28, 2016, and entitled “DISTRIBUTED LIDARSYSTEM”. The entireties of these applications are incorporated herein byreference.

FIELD OF THE INVENTION

The field of the invention is LiDAR systems, particularly frequencymodulated continuous wave LiDAR systems for use in vehicles.

BACKGROUND

The following description includes information that may be useful inunderstanding the present invention. It is not an admission that any ofthe information provided herein is prior art or relevant to thepresently claimed invention, or that any publication specifically orimplicitly referenced is prior art.

LiDAR's are becoming important in sensing applications in a variety offields associate with autonomous navigation. In particular, autonomousvehicles, UAV's and robotics rely on LiDAR to produce imaginginformation to be used, with or without information from other sensors,to guide the motion of those platforms. Currently, LiDAR systemsconsisting of an instrument head (where the light source, the lightdetectors, the transmission/steering optics, and the detection opticsare located) and control and processing assemblies used for the kind ofapplications made above are housed in a single housing, which is thenconnected to cables and wires for power and data transmission to acomputer or similar capability for image analysis. This implies that theentire package must be placed on the platform, at a location with accessto the area for which the imaging is required. For example, forapplications with advanced driver assisted systems (ADAS), the LiDARmust be placed on top of the car, or in other locations (say, under thefront grill) to have access to the road and roadside. This could bedifficult to implement, if the desire is to keep the package frominterfering with the structure of the body of the car. This is furthercomplicated if the package must be incorporated with active/passiveisolation assemblies to reduce the undesirable effects of shock andvibration that interfere with the proper operation of the LiDAR, orreduce its performance.

LiDAR can be accomplished in a variety of ways. In “time of flight”(TOF) LiDAR short pulses of light are emitted and reflected pulsesreceived, with the delay between emission and reception providing ameasure of distance between the emitter and the reflecting object. SuchTOF systems, however, have a number of disadvantages. For example simpleTOF measurements, in relying solely on the intensity of received light,are highly susceptible to interference from extraneous and irrelevantsignal sources. This issue becomes more pronounced as the distancebetween the emitter and the reflecting object increases, as suchdistance necessarily decreases the strength of the reflected signal. Onthe other hand, inherent limitations in accurately measuring extremelyshort time intervals limit the spatial resolution of such TOF LiDARsystems at close range. In addition, the range of such TOF LiDARs is afunction of the ability to detect the relatively faint reflected signal.The resulting range limitations are frequently addressed by using highlysensitive photodetectors. In some instances such detectors can detectsingle photons. Unfortunately this high degree of sensitivity also leadsto increased misidentification of interfering signals as reflect TOFLiDAR pulses from objects other than the target or from other lightsources. Despite these disadvantages TOF LiDAR systems currently findwide application, primarily due to the ability to provide such systemsin a very compact format and the ability to utilize relativelyinexpensive non-coherent laser light sources.

One approach to resolving this problem is to provide a ToF LiDAR systemin which system components are distributed about the vehicle. An exampleof such an approach is found in United States Patent Application No.2017/0153319 (to Villeneuve and Eichenholz). All publications identifiedherein are incorporated by reference to the same extent as if eachindividual publication or patent application were specifically andindividually indicated to be incorporated by reference. Where adefinition or use of a term in an incorporated reference is inconsistentor contrary to the definition of that term provided herein, thedefinition of that term provided herein applies and the definition ofthat term in the reference does not apply. In such an approach somecomponents of a ToF LiDAR system (such as transmitting scanner, inputfor gathering reflected light, and a receiver for characterizing thereflected light) can be positioned as a unit at one location of avehicle while another component (such as the light source) can bepositioned elsewhere. The distributed components can be connected usingconventional fiber optics and electrical cabling. The time-dependentnature of TOF LiDAR, however, requires proximity of the transmittingscanner, input, and receiver in order to retain timing fidelity. As aresult the scanning/receiving assembly of such systems remainsrelatively large and complex.

Alternatives to TOF LiDAR have been developed. One of these, frequencymodulated (FM) LiDAR, relies on a coherent laser source to generaterepeated waveforms representing a change of frequency with time or“chirps” of time delimited, frequency modulated optical energy. Thefrequency within waveform or chirp varies over time, and measurement ofthe phase and frequency of an echoing waveform or chirp relative to areference signal provides a measure of distance and velocity of thereflecting object relative to the emitter. Other properties of thereflected chirp (for example, intensity) can be related to color,surface texture, or composition of the reflecting surface. In addition,such FM LiDARs are relatively immune to interfering light sources (whichtend to produce non-modulated signals that are not coherent with thereceived signal) and do not require the use of highly sensitivephotodetectors.

Unfortunately, FM LiDAR systems that have been developed to date aregenerally not compact, as they rely on relatively large FMCW lasersources. In addition, such systems typically rely on a carefullymodulated, low noise local oscillator (for example, a narrow linewidthsolid state, gas, or fiber laser) with frequency modulationcorresponding to that of the emitted chirp provided by a relativelylarge interferometer. This local oscillator precisely replicates anemitted waveform or chirp, and serves as the reference for the receivedreflected signal. As a result FM LiDARs are typically large, complex,and expensive, and have seen limited implementation relative to TOFLiDARs despite their performance advantages.

Thus, there is still a need for effective and economical LiDAR systemsthat provide thorough coverage of the area surrounding a motor vehicle.

SUMMARY

Various objects, features, aspects and advantages of the inventivesubject matter will become more apparent from the following detaileddescription of preferred embodiments, along with the accompanyingdrawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B schematically depict a distributed FM LiDAR system ofthe inventive concept. System components are separated into a compact,lightweight optical head 120 including optical components and a signaland processing unit 105 that includes a frequency modulated pulse orchirp source and a receiver. FIG. 1A schematically depicts such a systemwith separate waveguides for outgoing and incoming frequency modulatedlight signals. FIG. 1B schematically depicts such a system that utilizesa common waveguide for outgoing and incoming frequency modulated lightsignals.

FIGS. 2A and 2B schematically depicts a distributed FM LiDAR system ofthe inventive concept, incorporating multiple optical heads in opticalcommunication with a central signal and processing unit. FIG. 2Aschematically depicts a system in which an optical router is utilized todistribute incoming and/or outgoing FM modulated optical chirps orpulses and is separate from a centralized signal and control unit. FIG.2B schematically depicts a system in which an optical router is utilizedto distribute incoming and/or outgoing FM modulated optical chirps orpulses and is positioned within a centralized signal and control unit.

DETAILED DESCRIPTION

The inventive subject matter provides apparatus, systems and methods inwhich a components of an FM LiDAR system are distributed in differentlocations around a vehicle, and interconnected with optical fiberwithout a need for the inclusion of optical delay lines or similarfeatures. For example, a compact and relatively simple optical head thatincludes a scanner and an input for reflected signals can be placed at adistance from a receiver for the reflected signals, the source laser,and other components of an FM LiDAR. The distributed components can beconnected by optical fibers, and do not require electricalcommunication. In addition, the relatively small and lightweight opticalhead can be conveniently placed in a wide variety of locations, and thereduced size and weight simplify shock and vibration control. In someembodiments two or more optical heads are distributed around a vehicleor trailer, and are connected with other components of an FM LiDARsystem (for example, a receiver for reflected signals, laser lightsource, etc.) using optical fibers and a routing device for opticalsignals.

One should appreciate that the devices and systems described hereinprovide distributed FM LiDAR systems that permit accurate identificationof objects, obstacles and vehicles using lightweight and robustcomponents suitable for placement in a wide variety of locations on orin a vehicle.

The following discussion provides many example embodiments of theinventive subject matter. Although each embodiment represents a singlecombination of inventive elements, the inventive subject matter isconsidered to include all possible combinations of the disclosedelements. Thus if one embodiment comprises elements A, B, and C, and asecond embodiment comprises elements B and D, then the inventive subjectmatter is also considered to include other remaining combinations of A,B, C, or D, even if not explicitly disclosed.

As used herein, and unless the context dictates otherwise, the term“coupled to” is intended to include both direct coupling (in which twoelements that are coupled to each other contact each other) and indirectcoupling (in which at least one additional element is located betweenthe two elements). Therefore, the terms “coupled to” and “coupled with”are used synonymously.

FM LiDAR systems of the inventive concept can include afrequency-modulated light source (such as an FM laser or FM laseroptical subsystem), an optical head that includes an optical scanningdevice for transmitting frequency modulated laser waveforms or chirps tothe environment and also includes an input for capturing reflectedpulses or chirps, and a receiver for receiving captured waveforms orchirps and converting the captured waveforms or chirps into electricalsignals. Such a system can also include a controller that receives suchelectrical signals and derives information related to the distance ofreflecting objects. Such a controller can also be coupled to the opticalscanner, and provide instructions for rate and direction of the scanningstream of optical pulses or chirps. Similarly, the controller can becoupled to the frequency-modulated laser light source, and provideinstructions for repeat rate, frequency ramp duration, frequency rampconfiguration, and/or other properties of waveforms, modulations, orchirps to be transmitted.

Any suitable frequency-modulated light source can be utilized to producefrequency modulated pulses or chirps for transmission by systems anddevices of the inventive concept. In some embodiments optical waveformsor chirps can be generated by applying a modulated bias current to awavelength-tunable laser diode in order to shift the instant frequencyof the emitted light. In other embodiments the output of a laser lightsource can be directed through an electro-optic or acousto-opticalmodulator to provide the necessary frequency shift. In such anembodiment a portion of the laser light can be directed through amodulator to provide a local oscillator signal.

In some embodiments devices and systems of the inventive concept canincorporate a laser source that is optically coupled to a whisperinggallery mode optical resonator as a frequency modulated light source.Light from the laser is coupled into a whispering gallery mode opticalresonator, and is coupled back out as a returning counterpropagatingwave having a frequency characteristic of a whispering gallery mode ofthe optical resonator. This returning wave can reduce the linewidth ofthe source laser by optical injection. Frequency modulated waveforms orchirps can be produced by modulating an optical property of thewhispering gallery mode optical resonator, which in turn results inmodulation of the frequency supported by whispering gallery modes of theresonator. Light with such modulated frequencies can be used to providefrequency modulated waveform or chirps from robust and low-cost laserlight sources, for example a semiconductor laser.

One embodiment of the inventive concept is a LiDAR system that includesa laser light source, a modulatable whispering gallery mode resonatorthat is optically coupled to the laser light source to provide linewidthreduction via optical injection (or, alternatively, electronic locking),a transducer that can alter an optical property of the whisperinggallery mode optical resonator (for example, refractive index), acontroller that controls the transducer, a transmission assembly fortransmitting optical chirps generated by the controller, a receiver thatreceives reflected optical frequency modulated waveforms or chirps, anda processor that utilizes data derived from the reflected frequencymodulated waveforms or chirps to determine position of an object that isreflecting the chirps. In some embodiments all of these components areprovided on a single substrate. The linewidth of the locked laser sourcecan be less than 1 kHz. In such an embodiment the laser source can alsoact as the source of a reference waveform, modulation, or chirp that iscombined with a reflected waveform, modulation, or chirp in determiningposition of a reflecting object.

In embodiments of the inventive concept the FM laser and the receiverare housed separately from an optical head that includes an opticalscanner (utilized to direct the frequency modulated light into theenvironment) and an optical input (utilized to receive reflected lightfrom the environment). As shown in FIG. 1A, the FM laser can be part ofan FM modulation, waveform, or chirp source 110, which can be housedwith a receiver 150 (which serves to convert received reflected lightinto electrical impulses) and a controller 160. In a preferredembodiment these components can be housed in a common signal processingunit (105) in common enclosure or housing 100, which can be positionedat a central or convenient position within the vehicle. Such a housingor enclosure 100 can be attached or otherwise coupled to a vibrationand/or shock reducing mounting in order to reduce or eliminate damage tothese relatively sensitive components.

As shown, components of such a signal and processing unit can be inoptical communication with an optical head 120. Optical communicationcan be provided by waveguides (115, 145), such as optical fibers. Forexample, an outgoing optical waveguide 115 can provide opticalcommunication between the FM chirp source 110 and a scanner/emitter 130of an optical head. Similarly, an incoming optical waveguide 145 candirect reflected light collected by an optical input 140 of an opticalhead 120 to a receiver 150 of the signal and processing unit 105.Although use of separate incoming and outgoing optical waveguides isshown in FIG. 1A, in some embodiments a common waveguide 115A can beused for outgoing frequency modulated waveforms or chirps and incominglight (which can include reflected frequency modulated waveforms orchirps), as shown in FIG. 1B. In some embodiments differentiationbetween outgoing frequency modulated waveforms or chirps and incomingfrequency modulated waveforms or chirps can, if necessary, be providedby an optical switch or router and/or by tracking the timing of thefrequency modulated waveforms or chirps. Such an optical switch orrouter can be located within the housing 100 or outside of the housing.

It should be appreciated that the optical head 120 can include onlyoptical components and related manipulators. For example, an opticalhead can include an optical scanner 130 (for example, an X/Y scanner)and an optical input 140 for reflected pulses or chirps. An opticalscanner can include one or more reflective surfaces coupled tomechanisms that control their orientation (such as motors and/orpiezoelectric devices), which permits scanning of a stream of pulses orchirps received by the optical scanner from a frequency-modulated lightsource (for example, via an optical fiber). A variety of mechanisms aresuitable for providing the scanning function, including rotating orgimbal-mounted mirrors, MEMs devices, a set of two or more mirrorsmounted on actuators (for example, electric motors, solenoids, and orpiezoelectric devices) in a mutually orthogonal fashion, rotatingprisms, and/or rotating lenses. An example of a suitable MEMs device isthe solid-state tripod mirror mount developed by MinFaros®. In someembodiments a phased array steering device can be used to provide ascanning function. Such a scanning function can be utilized to direct aseries of transmitted pulses or chirps in a pattern that sweeps an X-Yplane and/or interrogates a three dimensional volume.

An optical input 140 can include a device for gathering light that ispositioned to direct incoming, reflected light to an incoming waveguide145 that is optically coupled to a receiver 150, which can be located ata distance from the optical head. For example, a lens or mirror can bepositioned behind an optically transparent window of an optical head120. An input facet of a waveguide serving as an incoming optical fiber145 can be positioned at or near a focal point of the lens or mirror.

In some embodiments the position from which the emitted modulation,waveform, or chirp, or otherwise modulated light leaves the optical headand the position from which the reflected modulation, waveform, or chirpencounters the optical input are coaxial. In other embodiments theposition from which the emitted modulation, waveform, or chirp, orotherwise modulated light leaves the optical head and the position fromwhich the reflected modulation, waveform, or chirp, or otherwisemodulated light encounter the optical input are positioned on differentoptical axes. In a preferred embodiment the position from which theemitted modulation, waveform, or chirp, or otherwise modulated lightleaves the LiDAR system and the position from which the reflectedmodulation, waveform, or chirp, or otherwise modulated light encountersthe optical input are coaxial and proximal, so as to provide a compactdevice. In some embodiments the optical scanner and the optical inputare fabricated on a common surface, such as on a silicon chip or wafer,to provide an essentially unitary and/or solid-state device.

Since both the optical scanner and the optical input are simple andcompact the optical head can be relatively small and lightweight. Thispermits installation of an optical head of the inventive concept in awide variety of locations on a vehicle, for example behind a frontgrill, within a door or roof panel, inside of a bumper assembly, etc.The relatively small size and light weight also simplifies vibration andshock proofing. It should also be appreciated, particularly in view ofthe relatively exposed positions of such system components, that therelative simplicity of the optical head simplifies and reduces theexpense of repair and replacement.

In a preferred embodiment a single signal and processing unit 105 isoptically coupled to two or more optical heads (130A to 130F) usingoptical waveguides, as shown in FIGS. 2A and 2B. Such optical heads canbe arranged about the exterior of a vehicle to provide a distributedLiDAR system. The number and position of such optical heads can beselected to provide an overlap of the observed field available to eachoptical head, thereby providing complete LiDAR coverage around thevehicle. It should be appreciated that it is not necessary toincorporate optical delay lines or similar devices into the opticalwaveguides in order to correct for differences in time of flight betweenoptical chirps or pulses. Similarly, it is not necessary to calibratethe system or apply a corrective algorithm in order to correct fordifferences in time of flight between transmitted and received light andsignals. In some embodiments each optical head can be connected directlyto the signal and processing unit, which can include an optical routeror similar device that permits switching of incoming reflected lightfrom individual optical heads to a common receiver. In other embodimentsindividual optical heads can be connected to an optical switch, opticalrouter or similar device 170, which can direct frequency modulatedmodulation, waveform, or chirp, or otherwise modulated light from the FMmodulation, waveform, or chirp, or otherwise modulated light source 110to one or more optical head(s) 130 via outgoing optical fibers orwaveguides and/or direct light from reflected frequency modulatedmodulation, waveform, or chirp, or otherwise modulated light from one ormore optical head(s) 130 to a receiver 150 via incoming optical fibersor waveguides. In some embodiments, as shown in FIG. 2A, the opticalrouter 170 is located separately from the signal and processing unit105. In other embodiments, as shown in FIG. 2B, the optical router 170is located within the signal and processing unit 105.

The controller 160 can provide control of the frequency modulated FMmodulation, waveform, or chirp, or otherwise modulated light source, forexample providing a frequency modulated electrical signal utilized togenerate the desired FM modulation, waveform, or chirp. In someembodiments the controller can also receive electrical signals from thereceiver 150, which correspond to reflected light from the environment.In such embodiments the controller can include a processor and/oralgorithm that utilizes information content of the received electricalsignals to derive position data for a reflecting object within range ofan optical head. The controller can include one or more processingmodules, which can incorporate one or more microprocessors. Examples ofsuitable microprocessors include members of the SnapDragon® chips fromQualComm®. For example, a controller can include a fast Fouriertransform module for initial processing of combined data from reflectedchirps received from the environment and a reference, non-reflectedchirp. The transformed data from such a fast Fourier transform modulecan then be used to derive spatial coordinates and/or velocity of areflective surface that provided the reflected light. The controller 160can store and/or transmit such data derived from one or more reflectedFM modulation, waveform, or chirp, or otherwise modulated light in theform of a point cloud (i.e. a collection of data points representingspatial coordinates of reflecting surfaces). Such a point cloud can alsoencode information related to velocity and/or secondary information(such as color, texture, roughness, composition, etc.).

In some embodiments, an FM LiDAR of the inventive concept is integratedinto a vehicle assistance system. In such an embodiment the FM LiDAR canbe integrated into or mounted on (or in) a mobile vehicle (for example,a ground vehicle, an aircraft, a drone, and/or a watercraft). Forexample, a signal and processing unit 105 can be positioned at alocation that provides sufficient space for the signal and processingunit and requisite shock and vibration resistant mounting, whilemultiple optical heads can be distributed in appropriate positionsaround the exterior (or at least with optical access to the exterior) ofa vehicle. In such an embodiment the FM LiDAR can provide spatial datarelated to position and/or velocity of reflecting objects within thescanning range of the FM LiDAR system. Such a scanning range canrepresent a plane and/or a volume, depending upon the configuration ofthe FM LiDAR system. Such data can be represented as a point cloud,wherein each point represents at least 2D or 3D spatial coordinatesrelated to a reflecting object. In some embodiments characteristics ofthe reflected light (for example, amplitude and/or intensity) canprovide information related to additional characteristics of thereflecting object (for example, composition, color, surface texture,etc.). Values for such additional characteristics can be encoded in thepoints of the point cloud.

Such point cloud data can be utilized by on-board or off-boardprocessors to provide assistance to the operation of vehicles soequipped. In some embodiments such assistance can be in the form ofwarnings and/or prompts that are provided to a vehicle operator. Such avehicle operator can be present in the vehicle or can be piloting thevehicle remotely. In some embodiments assistance to a vehicle operatorcan be provided in the form of automated vehicle responses. Examples ofautomated vehicle responses include changes in speed (e.g. accelerating,decelerating, braking, etc.), altitude, and/or direction. Such automatedvehicle responses can be provided following prompting of the vehicleoperator or in an autonomous fashion. In some embodiments such automatedvehicle responses can override control of the vehicle provided by thevehicle operator, for example when detected conditions meet certaincriteria. Examples of such criteria include determination that adetected condition can result in injury to an operator and/or a detectedindividual, vehicle damage or loss, or require action that is more rapidthan can be provided by the operator.

In other embodiments of the inventive concept such point cloud data canbe utilized by on-board or off-board processors to provide a vehicle soequipped with the capability to operate autonomously. In someembodiments such an autonomous functionality can be at the discretion ofan onboard or remote vehicle operator. In such embodiments the vehiclecan be directed by the vehicle operator during part of its operation(for example, take off, landing, heavy pedestrian traffic, etc.) andoperate autonomously under other conditions. In other embodiments avehicle so equipped operates wholly autonomously. Such an autonomousvehicle can be configured to carry passengers (i.e. persons not involvedin operating the vehicle), or can be designed to operate without a humanpresence.

In some embodiments of the inventive concept, a distributed LiDAR systemthat includes a single signal and processing unit (incorporating a FMmodulation, waveform, or chirp, or otherwise modulated light source, areceiver for transforming reflected light into an electronic impulse, acontroller, and, optionally, an optical switch or router) and multipleoptical heads (incorporating an optical scanner and an optical input forreflected light) that are connected by optical waveguides can beincorporated into a motor vehicle. In some embodiments the components ofsuch a distributed LiDAR system are distributed about a discrete vehicle(such as an automobile, watercraft, or aircraft), with shock andvibration protection provided for the signal and processing unit. Inother embodiments the components of such a distributed LiDAR system aredistributed between a primary vehicle (which can include a driver and/oran autonomous driving system) and a coupled secondary vehicle that ispassively directed and/or towed by the primary vehicle. Such a secondaryvehicle can include an engine or motor that provides motive force forthe secondary vehicle, or can lack an engine or motor such that motiveforce is provided by the primary vehicle. In some embodiments thesecondary vehicle can include steering and/or braking mechanisms thatare directed by the primary vehicle. For example, the signal andprocessing unit (and, optionally, one or more optical head(s)) can beinstalled in or on a cab portion of a commercial transport truck thatprovides motive power and primary steering, and one or more opticalhead(s) can be installed in or on one or more trailer(s) that is(are)coupled to and pulled by the cab and that provides braking for thetrailer(s) that is(are) under the direction of the cab, with connectionsbetween these components provided by optical fibers or waveguides. Insuch embodiments an optical connector can be provided between theprimary vehicle and the secondary vehicle that provides an optical linkbetween one or more optical fibers or waveguide(s) associated with oneor more optical head(s) mounted in or on the secondary vehicle and oneor more waveguide(s) associated with the signal and processing unitlocated on or in the primary vehicle.

In some embodiments of the inventive concept a distributed FM LiDAR ofthe inventive concept can be incorporated into an Advanced DriverAssistance System (ADAS). Such systems provide automated/adaptive and/orenhanced vehicle systems that improve safety while driving. Such systemsare designed to avoid collisions and accidents, by utilizingtechnologies that alert a driver to potential problems, or to avoidcollisions by assuming control of the vehicle. ADAS can provide adaptivefeatures such as automated lighting, adaptive cruise control, andautomated braking, and can incorporate GPS/traffic warnings, connectwith a smartphone and/or a data cloud. Such systems can alert a driverto the presence and/or proximity of other vehicles or obstacles, keepthe vehicle in a desired traffic lane, and/or provide a driver with adisplay of what is not visible via the vehicle's mirrors.

In other embodiments an ADAS system incorporating a distributed FM-LiDARof the inventive concept can provide instructions to systems that directthe movement of the vehicle. For example, such an ADAS system canprovide instructions that trigger an actuator that manipulatescomponents of the vehicle's brake system, steering system, and/or engineaccelerator. In such an embodiment the system can augment a vehicleoperator's actions or, alternatively, permit the vehicle to operate inan autonomous or semi-autonomous fashion. In other embodiments such aADAS system can provide instructions to a vehicle system that is, atleast in part, operating the vehicle. For example, such an ADAS enginecan provide instructions to a cruise control system, which in turnprovides instructions to actuators coupled to various vehicle operatingcomponents. Alternatively, an ADAS system of the inventive concept canprovide instructions to an autonomous driving system that operates thevehicle without the need for direct action by a vehicle operator.

It should be apparent to those skilled in the art that many moremodifications besides those already described are possible withoutdeparting from the inventive concepts herein. The inventive subjectmatter, therefore, is not to be restricted except in the spirit of theappended claims. Moreover, in interpreting both the specification andthe claims, all terms should be interpreted in the broadest possiblemanner consistent with the context. In particular, the terms “comprises”and “comprising” should be interpreted as referring to elements,components, or steps in a non-exclusive manner, indicating that thereferenced elements, components, or steps may be present, or utilized,or combined with other elements, components, or steps that are notexpressly referenced. Where the specification claims refers to at leastone of something selected from the group consisting of A, B, C . . . andN, the text should be interpreted as requiring only one element from thegroup, not A plus N, or B plus N, etc.

What is claimed is:
 1. A distributed lidar system, comprising: a signalprocessing unit in a housing, the signal processing unit comprising: afrequency modulated light source in the housing, the frequency modulatedlight source configured to provide a frequency modulated waveform; and areceiver in the housing, the receiver configured to transform areflected frequency modulated waveform into an electrical signal; and afirst optical head separate from the housing, the first optical headcomprising: a first optical scanner in optical communication with thefrequency modulated light source, the first optical scanner configuredto transmit the frequency modulated waveform into an environment; and afirst optical input in optical communication with the receiver, theoptical input configured to receive the reflected frequency modulatedwaveform from the environment; a second optical head separate from thehousing, the second optical head comprising: a second optic scanner inoptical communication do with the frequency modulated light source; anda second optical input in optical communication with the receiver; atleast one waveguide that provides optical communication between thesignal processing unit and the first optical head; and at least onediffering waveguide that provides optical communication between thesignal processing unit and the second optical head.
 2. The distributedlidar system of claim 1, the frequency modulated light source comprisinga laser source optically coupled to a whispering gallery mode opticalresonator.
 3. The distributed lidar system of claim 1, the signalprocessing unit further comprising: a controller in the housing, thecontroller configured to derive information indicative of a distance toan object in the environment based on the electrical signal.
 4. Thedistributed lidar system of claim 1, the signal processing unit furthercomprising: a controller in the housing, the controller configured toprovide a frequency modulated electrical signal, the frequency modulatedelectrical signal causes the frequency modulated light source togenerate the frequency modulated waveform.
 5. The distributed lidarsystem of claim 1, wherein the housing of the signal processing unit iscoupled to a shock and vibration resistant mounting.
 6. The distributedlidar system of claim 1, the signal processing unit further comprising:an optical router in the housing, the optical router configured toswitch between the first optical input and the second optical input. 7.The distributed lidar system of claim 1, further comprising: an opticalrouter separate from the housing, the optical router configured toswitch between the first optical input and the second optical input. 8.The distributed lidar system of claim 1, the at least one waveguidecomprising: a first waveguide that provides optical communicationbetween the frequency modulated light source in the housing and thefirst optical scanner; and a second waveguide that provides opticalcommunication between the first optical input and the receiver in thehousing.
 9. The distributed lidar system of claim 1, the first opticalinput further configured to direct the reflected frequency modulatedwaveform to the waveguide.
 10. The distributed lidar system of claim 1,wherein a position from which the frequency modulated waveform leavesthe first optical scanner and a position at which the reflectedfrequency modulated waveform encounters the first optical input arecoaxial.
 11. The distributed lidar system of claim 1, wherein the firstoptical scanner and the first optical input are fabricated on a commonsurface.
 12. The distributed lidar system of claim 1, wherein the signalprocessing unit and the first optical head lack electrical communicationtherebetween.
 13. The distributed lidar system of claim 1 being in avehicle.
 14. A vehicle, comprising: a distributed lidar system,comprising: a signal processing unit in a housing, the signal processingunit comprising: a frequency modulated light source in the housing, thefrequency modulated light source configured to provide a frequencymodulated waveform; and a receiver in the housing, the receiverconfigured to transform a reflected frequency modulated waveform into anelectrical signal; and a first optical head at a first location in thevehicle separate from the housing, the first optical head comprising: afirst optical scanner in optical communication with the frequencymodulated light source, the first optical scanner configured to transmitthe frequency modulated waveform into an environment; and a firstoptical input in optical communication with the receiver, the firstoptical input configured to receive the reflected frequency modulatedwaveform from the environment; a second optical head at a secondlocation in the vehicle separate from the housing, the second opticalhead comprising: a second optical scanner in optical communication withthe frequency modulated light source; and a second optical input inoptical communication with the receiver; at least one waveguide thatprovides optical communication between the signal processing unit andthe first optical head; and at least one differing waveguide thatprovides optical communication between the signal processing unit andthe second optical head.
 15. The vehicle of claim 14, furthercomprising: an optical connector; wherein a secondary vehicle is coupledto the vehicle, the secondary vehicle comprising a third optical head,the third optical head comprising: a third optical scanner in opticalcommunication with the frequency modulated light source via the opticalconnector of the vehicle; and a third optical input in opticalcommunication with the receiver via the optical connector of thevehicle.
 16. The vehicle of claim 14, wherein at least one of the firstoptical head or the second optical head is behind a front grill of thevehicle.
 17. The vehicle of claim 14, wherein at least one of the firstoptical head or the second optical head is in a door of the vehicle. 18.The vehicle of claim 14, wherein at least one of the first optical heador the second optical head is in a bumper assembly of the vehicle. 19.An autonomous vehicle, comprising: a distributed lidar system,comprising: a signal processing unit in a housing, the signal processingunit comprising: a frequency modulated light source in the housing, thefrequency modulated light source configured to provide a frequencymodulated waveform; a receiver in the housing, the receiver configuredto transform a reflected frequency modulated waveform into an electronicsignal; a controller in the housing, the controller configured to deriveinformation indicative of a distance to an object in an environmentbased on the electrical signal; and a first optical head at a firstlocation in the autonomous vehicle separate from the housing, the firstoptical head comprising: a first optical scanner in opticalcommunication with the frequency modulated light source, the firstoptical scanner configured to transmit the frequency modulated waveforminto the environment; and a first optical input in optical communicationwith the receiver, the first optical input configured to receive thereflected frequency modulated waveform from the environment; a secondoptical head at a second location in the autonomous vehicle separatefrom the housing, the second optical head comprising: a second opticalscanner in optical communication with the frequency modulated lightsource; and a second optical input in optical communication with thereceiver; at least one waveguide that provides optical communicationbetween the signal processing unit and the first optical head; and atleast one differing waveguide that provides optical communicationbetween the signal processing unit and the second optical head; at leastone processor in communication with the distributed lidar system, the atleast one processor configured to enable the autonomous vehicle toautonomously operate, the at least one processor autonomously operatesbased at least in part on the information indicative of the distance tothe object in the environment.
 20. The vehicle of claim 14, thefrequency modulated light source comprising a laser source opticallycoupled to a whispering gallery mode optical resonator.